Former members of the special forces have expressed concern at a costcutting plan that that could lead to Britain’s elite military units being shrunk by up to 40 per cent.

The proposals, drawn up by the director of special forces, include taking the two reservist regiments of the Special Air Service (SAS) — 21 SAS and 23 SAS — out of the special forces command chain and attaching them to the regular Army reserves.

Another possibility is reducing the Special Boat Service (SBS) from four squadrons to three — a move that triggered suspicion of a turf war erupting within the special forces